UNIT 6 - GENETIC MUTATIONS Flashcards
Gene Mutation or Chromosomal Mutation
A single gene is affected
Gene Mutation
Gene Mutation or Chromosomal Mutation
Several genes are affected
Chromosomal Mutation
Gene Mutation or Chromosomal Mutation
Alteration of the nucleotide sequence
Gene Mutation
Gene Mutation or Chromosomal Mutation
Alterations in the chromosome structure or number
Chromosomal Mutation
Gene Mutation or Chromosomal Mutation
Caused by errors in DNA ____ and mutagens
Gene Mutation
Replication
Gene Mutation or Chromosomal Mutation
Caused by errors in crossing over during meiosis
Chromosomal Mutation
A gene variant present in more than one percent of a population
Polymorphism
True or False
A mutation is not always a change from wild type
True
Which of the following statements is true about mutations?
A. They can produce new alleles of existing genes.
B. They can be inherited if they are in somatic cells.
C. They are never as simple as an error in a single codon in a DNA molecule.
D. A and B
A
True or False
Genetic Polymorphism is not associated with any disease
True
Variants in other
genes that counteract the loss of function
Made to silence or kill the expression of a specific gene
Knockouts
A ____ is any heritable change in the amount or structure of genetic material
Mutation
True or False
Natural selection does affects the alleles that bring polymorphism
False
Natural selection does not affect the alleles that bring polymorphism
Polymorphism or Mutation
A permanent alteration of a nucleotide sequence of a gene
Mutation
True or False
In polymorphism, a single base pair exchange is called a point mutation
False
Mutation, not polymorphism
True or False
In polymorphism, a single base pair exchange in the nucleotide sequence is called a ____ ____ ____
Single Nucleotide Polymorphism
Classification of mutations can be based on all, except:
A. Origin
B. Cell Type
C. Expression
D. Effect on Function
E. Molecular Change
F. None of the above
F. None of the above
True or False
There is a direct relationship between the mutation rate and the size of a genome
False
Inverse relationship
The larger the genome, the smaller the mutation rate
True or False
A large population of certain species means there will be high mutation rates
False
Mutation rates are inversely proportional to population sizes of species
The ____ of DNA polymerase involves its ability to correct changes in the DNA and the accuracy with which the DNA sequence is copied
Fidelity
Based on Origin
Occurs in the absence of a known mutagen
Mutations based on origin
Spontaneous
Based on Origin
Occurs in the presence of a known mutagen
Mutations based on origin
Induced
Spontaneous mutations are similar to (endogenous, exogenous) mutations
Mutations based on origin
Endogenous
Having an internal cause or origin
E____ refers to the random accumulation of deleterious mutations
Mutations based on origin
Entropy
This mutagen causes congenital malformations; affects pluripotent stem cells
Mutations based on origin
Teratogens
This mutagen causes tumor formation; involves cancer-causing agents
Mutations based on origin
Carcinogens
This mutagen causes chromosomal abnormalities or breaks in chromosomes that result in the gain, loss, or rearrangements of chromosomal segments
Mutations based on origin
Clastogens
This mutagen causes DNA damage
Mutations based on origin
Non-specific
Physical, Chemical, or Biological Mutagens?
Ionizing radiations, Non-ionizing radiations, Heat
Mutations based on origin
Physical mutagens
Physical, Chemical, or Biological Mutagens?
Alkylating agents, Deaminating agents, Intercalating agents
Mutations based on origin
Chemical mutagens
Physical, Chemical, or Biological Mutagens?
Biological agents, Biological infectious agents
Mutations based on origin
Biological mutagens
Viruses, Bacteria, and Transponons are under what class of mutagens?
Mutations based on origin
Biological mutagens
Natural elements of DNA that jump from one place to another within a genome
Also called “jumping genes”
Transponons
Exogenous or Endogenous
UV-Light
Mutations based on origin
Exogenous
Exogenous or Endogenous
Smoking
Mutations based on origin
Exogenous
Exogenous or Endogenous
Spontaneous or enzymating DNA base modifications
Mutations based on origin
Endogenous
Exogenous or Endogenous
DNA replication errors
Mutations based on origin
Endogenous
True or False
Reactive oxygen species are both exogenous and endogenous sources of mutation
Mutations based on origin
True
Dipyrimidine photoproducts (CPD, 6-4PP) are caused by
Mutations based on origin
UV-light
Bulky DNA adducts at guanines (BPDE-dG) are caused by
Mutations based on origin
Smoking
A pair of abnormally chemically bonded adjacent thymine Bases in DNA, resulting from damage by ultra-violet irradiation
Mutations based on origin
Thymine dimers
DNA repair enzymes that repair damage caused by exposure to ultraviolet light
Mutations based on origin
Photolyases
Not present in humans
A rapid, transient, production of huge amounts of reactive oxygen species; acts as a defence mechanism to pathogen infection in plants
Mutations based on origin
Oxidative burst
Mechanisms of repair for DNA replication errors
Mutations based on origin
Nucleotide excision repair
Base incision repair
Mismatch repair
Three Types of Chemical Mutagens
Mutations based on origin
Base analogs
Base altering agents
Intercalating agents
Types of base altering agents in chemical mutagens
Mutations based on origin
Deaminating agents
Hydroxylating agents
Alkylating agents
Type of mutation that occurs in nonreproductive cells
Mutations based on cell type
Somatic
Mutations can be caused by all of the following except:
A. radiation
B. some chemicals
C. incest
D. some microorganisms
E. none of the above
Mutations based on origin
C. incest
Incest does not increase the likelihood of mutations occurring
In order for a mutation to be selected for or against by natural selection, it must:
A. be a gross chromosomal rearrangement or an irregular number of chromosomes
B. occur in the genotype
C. be expressed in the phenotype
C. be expressed in the phenotype
The following are true for somatic mutation, except:
A. Happens during DNA replication before mitosis
B. Passed to the next generation of cells
C. Passed to all the cells in the individual’s body
D. All the cells that descend from the original changed cell are altered, but they might only comprise a small part of the body
Mutations based on cell type
C
Somatic mutations are not passed to all cells in the body
True or False
A person with somatic mutations will have mosaicism
Mutations based on cell type
True
True or False
Most expression of germline mutations is in the form of cancer
Mutations based on cell type
False
Somatic mutations, not germline
In this mutation, only one area/organ of the body is usually affected
Mutations based on cell type
Somatic mutation
This type of mutation occurs in reproductive cells and can be inherited
Mutations based on cell type
Germline mutations
True or False
In germline mutations, the resulting gamete and all the cells that descend from it after fertilization have the mutation—that is, every cell in the body
Mutations based on cell type
True
Which germ cell is more commonly related to de novo mutations?
Mutations based on cell type
Sperm cells
True or False
Egg cells are associated with aneuploidy rather than mutations
Mutations based on cell type
True
A mutation that is expressed only under restrictive conditions
Expressed only under certain conditions
Mutations based on expression
Conditional
In unconditional mutations, the effect of mutation can be turned on or off by the experimenter
Mutations based on expression
False
Unconditional mutations are expressed all of the time; Conditional dapat
A mutation that is expressed under permissive conditions as well as restrictive conditions
Mutations based on expression
Unconditional
Example of unconditional mutations
Mutations based on expression
Hemophilia
Sickle cells
Loss of function mutations are also called A____
Mutations based on effect on function
Amorphic
This type of mutation results in complete gene inactivation or in a completely nonfunctional gene product; eliminates normal function
Mutations based on effect on function
Loss of function/Amorphic
This type of mutation reduces normal function, but does not eliminate the level of expression of a gene or the activity of the gene product
Mutations based on effect on function
Hypomorphic (Leaky mutation)
True or False
Leaky mutations show up in both restrictive and permissive conditions
Mutations based on effect on function
False
Restrictive only
This type of mutation increases normal function and produces a greater-than-normal level of gene expression
Mutations based on effect on function
Hypermorphic
This type of mutation changes the regulation of the gene so that the gene product is overproduced
Mutations based on effect on function
Hypermorphic
Neomorph mutation is also called ____ expression
Mutations based on effect on function
Ectopic
This type of mutation results in a new function – expressed at an incorrect time or in an inappropriate cell
Mutations based on effect on function
Neomorph
True or False
Neomorphic mutations quantitatively alters the action of a gene
Mutations based on effect on function
False
Qualitative, not quantitative
This type of mutation causes a gene to become active in a type of cell or tissue in which the gene is not normally active
Mutations based on effect on function
Neomorph
This type of mutation involves a mutant gene product which interferes with normal gene product
Mutations based on effect on function
Antimorphic
Gain or loss of function?
Antimorphic mutations
Mutations based on effect on function
Loss of function
Gain or loss of function?
Neomorphic mutations
Mutations based on effect on function
Gain of function
Gain or loss of function?
Hypermorphic mutations
Mutations based on effect on function
Gain of function
Gain or loss of function?
Hypomorphic/Leaky mutations
Mutations based on effect on function
Loss of function
Recessive mutations are usually a ____ of function
Mutations based on effect on function
Loss
What are the types of mutations based on molecular change?
Mutations based on molecular change
Substitutions
Deletions
Insertions
Duplications
Inversions
Translocations
This type of mutation involves the replacement of a single nucleotide by another
Mutations based on molecular change
Substitutions
Transition or Transversion
Replacement by the same type of nucleotide
Mutations based on molecular change
Transition
Transition or Transversion
Pyrimidine to Purine
Purine to Pyrimidine
Mutations based on molecular change
Transversion
Which transition is more frequent?
Pyrimidine to Pyrimidine or Purine to Purine?
Mutations based on molecular change
Pyrimidine to Pyrimidine
Due to CpG dinucleotides
Short stretches of DNA with an unusually high GC content and a higher frequency of CpG dinucleotides
Mutations based on molecular change
CpG islands
Which is worse?
Transitions or Transversions?
Mutations based on molecular change
Transversions
True or False
There is one possibility in transversions
Mutations based on molecular change
False
There are two possible transversions
What charactersitic of the genetic code saves the amino acid sequence from transitions?
Mutations based on molecular change
Degeneracy or Wobble
This type of mutation involves the loss of one or more nucleotides
Mutations based on molecular change
Deletions
Patterns of deletion
Mutations based on molecular change
Multiple of 3 nucleotides (codon)
Not multiple of 3
Large deletion
This type of deletion pattern arises through unequal crossover between repeat sequences
Mutations based on molecular change
Large deletion
True or False
Large deletion results in improper pairing during meiosis
Mutations based on molecular change
True
Which likely results in a frameshift mutation?
Indels with a multiple of 3 or not a multiple of 3
Mutations based on molecular change
Not a multiple of 3
Classical or Molecular Genetics
Point mutations are refered to as any mutation small enough to be unobservable under a light microscope
Mutations based on molecular change
Classical Genetics
Classical or Molecular Genetics
Point mutations are refered to as a single base-pair mutations
Mutations based on molecular change
Molecular Genetics
A one-base change in the sequence of one side that merits a change on the base of the complementary sequence
Mutations based on molecular change
Point mutation
Cystic fibrosis is an example of what type of mutation?
Mutations based on molecular change
Three-base deletion
What amino acid is missing in cystic fibrosis?
Mutations based on molecular change
amino acid 508 (phenylalanine)
What is the role of phenylalanine in protein synthesis?
Mutations based on molecular change
Contributes to the structural framework and functionality of proteins by forming peptide bonds during translation
This type of mutation involves the addition of one or more nucleotides into a gene
Mutations based on molecular change
Insertion
Amplification of a sequence of three nucleotides, which prevents normal expression of the gene
Mutations based on molecular change
Trinucleotide Repeat Expansion (TNR)
What disease is caused by expansion of trinucleotide repeats?
Mutations based on molecular change
Huntington’s Disease
True or False
Trinucleotide Repeat Expansions do not actually code for proteins, they just prolong the portion of the gene
Mutations based on molecular change
True
Trinucleotide Repeat Expansion disorder involving CGG repeats
Mutations based on molecular change
Fragile X Syndrome
Trinucleotide Repeat Expansion disorder involving CAG repeats
Mutations based on molecular change
Huntington Disease
Trinucleotide Repeat Expansion disorder involving CTG repeats
Mutations based on molecular change
Myotonic dystrophy
Trinucleotide Repeat Expansion disorder involving GAA repeats
Mutations based on molecular change
Friedreich ataxia
What gene is affected in Fragile X syndrome?
Mutations based on molecular change
FMR1 gene
What gene is affected in Huntington’s Disease?
Mutations based on molecular change
HTT gene
What gene is affected in Myotonic dystrophy?
Mutations based on molecular change
DMPK gene
What gene is affected in Friedreich ataxia?
Mutations based on molecular change
FXN1 gene
Fragile X Syndrome Mutation
30 CGG permutations
Mutations based on molecular change
Wild-type allele
Fragile X Syndrome Mutation
50-200 CGG permutations
Mutations based on molecular change
Premutation
Fragile X Syndrome Mutation
> 230 CGG permutations
Mutations based on molecular change
Mutant allele
Synonymous or Nonsynonymous Mutations
Silent mutations are classified as
Mutations based on their effect on protein products
Synonymous Mutations
Types of Nonsynonymous Mutations
Mutations based on their effect on protein products
Missense mutations
Nonsense mutations
Frameshift mutations
True or False
Synonymous mutations do not alter the polypeptide product of the gene
Mutations based on their effect on protein products
True
No effect on the protein sequence
This nonsynonymous mutation involves base-pair substitutions that produce a change in a single amino acid
Mutations based on their effect on protein products
Missense mutations
Missense, Nonsense, or Frameshift?
Nonpolar amino acid is replaced with a polar amino acid
Mutations based on their effect on protein products
Missense
A type of missense mutation that results in the substitution of similar but not identical amino acids
Same functional group
Mutations based on their effect on protein products
Conservative Missense Mutation
A type of missense mutation where the alteration in nucleotide causes the formation of a completely different kind of amino acid in the chain
Mutations based on their effect on protein products
Non-conservative Missense Mutation
True or False
Sickle cell anemia is an example of a missense mutation
Mutations based on their effect on protein products
True
What position and chain is the change of amino acids in sickle cell anemia?
Mutations based on their effect on protein products
Position 6, Beta chain
Amino acid ____ ____ is replaced with ____ in sickle cell anemia
Mutations based on their effect on protein products
Glutamic acid, Valine
What is the abnormal hemoglobin product of the single nucleotide substitution in sickle cell anemia?
Mutations based on their effect on protein products
Hemoglobin S (HbS)
A type of nonsynonymous mutation that involves base-pair substitutions that produce a stop codon in the mRNA
Mutations based on their effect on protein products
Nonsense Mutations
This type of mutation results in a premature termination of the polypeptide chain
Mutations based on their effect on protein products
Nonsense Mutations
Beta-0 thalassemia is an example of what type of nonsynonymous mutation?
Mutations based on their effect on protein products
Nonsense Mutations
True or False
Beta-0 thalassemia is a heterozygous phenomenon
Mutations based on their effect on protein products
False
Homozygous
What amino acid is affected in Beta-0 thalassemia? What is substituted?
Mutations based on their effect on protein products
Glutamine (CAG), U is substituted for C (UAG)
Transition or Transversion
Beta-0 thalassemia
Transition
Frameshift mutations are also called i____
indels
A mutation that involves the insertion or deletion of nucleotides that are not a multiple of three, where the reading frame is altered
Frameshift mutation
Tay-Sachs disease is what type of mutation?
Frameshift mutation
Four base insertion in the hexosaminidase A gene
True or False
In frameshift mutations, the resulting amino acid sequence bears no resemblance to the normal sequence
True
The O allele is a result of what type of mutation?
Frameshift mutation
Single-base deletion at the ABO (glycosyltransferase) locus
A genetic mutation that inserts, deletes or changes a number of nucleotides in the specific site at which splicing takes place during the processing of precursor messenger RNA into mature messenger RNA
Splice site mutation
Partial or Whole gene duplication or insertion
May result in premature termination with loss of function or expression
Partial gene duplication or insertion
Type of mutation that involves aberrant splicing–exon skipping or intron retention
Splice site mutation
DNA point mutations _____.
A. Have no effect because of the redundancy of the nucleotide code.
B. Causes an incorrect amino acid, but no change in the overall protein.
C. Always leads to a nonfunctional protein.
D. Can lead to a nonfunctional protein or can have little effect depending on the position of the mutation.
E. Lead to the formation of an alternative protein structure, but the function of the protein doesn’t change.
D.
